MUON Collaboration meeting at Mission Inn, Riverside, California January 27 - 30, 2004
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MUON Collaboration meeting at Mission Inn, Riverside, California January 27 - 30, 2004 Development of the curved beryllium window Stephanie Yang & Wing Lau – Oxford Steve Virostek & Derun Li -- LBL
description
MUON Collaboration meeting at Mission Inn, Riverside, California January 27 - 30, 2004. Development of the curved beryllium window. Stephanie Yang & Wing Lau – Oxford Steve Virostek & Derun Li -- LBL. A short summary of the FEA work carried out on the Beryllium Window. Summary - PowerPoint PPT Presentation
Transcript of MUON Collaboration meeting at Mission Inn, Riverside, California January 27 - 30, 2004
MUON Collaboration meeting at Mission Inn, Riverside, California
January 27 - 30, 2004
Development of the curved beryllium window
Stephanie Yang & Wing Lau – Oxford
Steve Virostek & Derun Li -- LBL
A short summary of the FEA workcarried out on the Beryllium
Window
Summary
A new window geometry has been developed with the aim toreduce the thermal stresses which were considered to be on the high side in the previous window geometry although they are still below the allowable stress limit.
The new window has its intersection between the concave andthe convex region shifted away from the edges, thereby makingit slightly more flexible to allow freer thermal expansion.The pre-bow, before any thermal deformation, is kept to within30mm which is considered to be acceptable to the cavity as faras space is concerned
The new window geometry is shown in the next page. Threewindow thickness have been studied and all found to haveachieved acceptable thermal stresses.
Temp. distribution along the Window
0
20
40
60
80
100
120
0 50 100 150 200
Radial distance from centre (mm)
Te
mp
era
ture
C
Prescribed temp profile along window
Stress distribution: Max. approx 150 MPa
Zoom in on high stress area
Deflection due to thermal load. Max 1.72mm
Linear static runsWindow geometry:
Diameter: 16cm; Thickness: 0.25mm
0.25mm thk 0.38mm thk 0.5mm thk
2-D axisymodel
3-D plate model
2-D axisy model
3-D plate model
2-D axisy model
3-D plate model
1st freq.
463 Hz.
482 Hz
559 Hz
582 Hz
635 Hz
660 Hz
2nd freq.
1878 Hz
586 Hz
2190 Hz
703 Hz
2449 Hz
793 Hz
3rd freq.
2343 Hz
586 Hz
2782 Hz
704 Hz
3140 Hz
793 Hz
4th freq.
3254 Hz
820 Hz
3890 Hz
1050 Hz
4423 Hz
1250 Hz
5th freq.
3849 Hz
820 Hz
4690 Hz
1050 Hz
5433 Hz
1250 Hz
1st mode shape of the 3-D model
2nd mode shape of the 3-D model
3rd mode shape of the 3-D model
4th mode shape of the 3-D model
5th mode shape of the 3-D model
1st mode shape of the 2-D model
2nd mode shape of the 2-D model
3rd mode shape of the 2-D model
4th mode shape of the 2-D model
5th mode shape of the 2-D modelSummary of the natural frequency runs
Summary Conclusion:
By shifting the junction between the concave and the convex surface away from the rim, the revised geometry makes the window more flexible than the previous design. This is good news if the loading is purely thermal as it allows expansion to develop more freely, hence less thermal stresses;Comparing with the results shown in the previous window design which has concave radius larger than the convex radius, the current window has an increased bow and the reduced natural frequency. This indicates that the current window is more flexible;On a like with like comparison, the current window geometry has its peak stress almost halved, and if one opts for the 0.5mm thick window which expects a peak temperature of only 50C at the Window centre (See Steve Virostek’s memo), the peak thermal stress is less than 100 MPa which is well below the stress limit for this material;The natural frequencies are in general well below those obtained from the previous window geometry. This may or may not be acceptable for the physics requirement.Uni-directional bowing is expected even if the inner surface is at a higher temperature than the outer surface.
